1. Field of the Invention
The present invention relates to a mobile storage system including an anti-tip construction for preventing tipping of the individual mobile storage units. More particularly, the invention relates to such a system for modular, laterally oriented mobile storage
2. Description of the Related Art
Mobile storage systems are known in which storage units are supported on wheels or rollers and travel along tracks. The storage units are easily moved, enabling multiple units to be closely spaced with access to a particular unit gained by moving certain units out of the way. In lateral storage systems, the direction of travel of the storage units is parallel to the length of the storage units. Rows of storage units are closely spaced front to back. A rearward unit is accessed by rolling one or more forward units to the side to expose the rearward unit.
However, without the provision of an anti-tip arrangement, these mobile systems are subject to certain governmental safety restrictions. More specifically, OSHA regulations prohibit mobile storage units without an anti-tipping arrangement from exceeding a height-to-width ratio of 4 to 1.Accordingly, a typical two foot wide storage unit is limited to a height of eight feet. Furthermore, the California Seismic Safety Authority has ruled that all mobile storage systems installed in California must include anti-tip systems due to the additional hazards caused by earthquakes.
A common type of anti-tip system involves the use of upper bracing systems which fixedly mount to the ceiling, an adjacent wall, or on columns extending up from the floor. These bracing systems are coupled with the upper portions of the storage units to prohibit their tipping. This type of arrangement, however, is complex, expensive to fabricate and install, and produces an unsightly appearance. Moreover, one must additionally verify that the ceiling, wall, or columns are sufficiently strong to resist the extra loads imposed.
Another type of anti-tip system is that manufactured and sold by Kardex, Inc. which includes specially designed carriages and carriage tracks. More particularly, the carriage tracks have raised outer edges which define narrow grooves with the floor. The carriages have cooperating L-shaped flanges which are received within the defined groove to prevent the shelving units from tipping over. Although this arrangement eliminates many of the above-mentioned shortcomings, such a system still includes several problems. More particularly, large stresses are generated within the track to offset the great moment forces invariably produced by the tipping. Accordingly, the carriage tracks must be extremely strong and rigid to sufficiently offset the risk of structural failure. Additionally, these anti-tip systems cannot be readily retrofitted to existing mobile storage systems.
Yet another type of anti-tip system is disclosed in U.S. Pat. No. 4,911,507 to Leist, and entitled MOBILE STORAGE SYSTEM WITH ANTI-TIP CONSTRUCTION, which uses a separate retainer track affixed to the floor parallel to a nearby shelf track. The retainer track is generally Z-shaped with a horizontal flange spaced above the floor and forming a recess therebetween. An L-shaped retainer flange is affixed to the shelf carriage and has a horizontal finger extending into the recess. The retainer prevents the flange from lifting, thereby preventing the shelf unit from tipping. While this system satisfies some of the aforementioned shortcomings, it has certain drawbacks. Often the floor will be made of concrete and special tools and skills will be required to affix the retainer track to the floor.
Therefore, there is an unmet need for an anti-tip mobile storage system that is retrofittable to existing storage systems yet easily installed in proper alignment.